Brutus was an individual who was lured by the conspirator’s arguments about Rome needing to be a republic. In that sense Brutus's decision to betray his friend Caesar was initiated by the combined effort of the conspirators.

Anton is devastated by Caesar's death, but he also sees it as a way to gain political power. Caesar was his friend and leader, but Antony will quickly move on and use Caesar's murder to his own political advantage.